[RndTbl] Big-endian RAID5 recovery problem

Adam Thompson athompso at athompso.net
Mon May 1 16:39:07 CDT 2017

So I've got 4 IDE HDDs, each with 3 RAID partitions on them, that were 
part of a RAID array in a now-very-dead NAS.

Of course, I need to get data off them that wasn't backed up anywhere 

I've got a 4-port USB3 PCIe card, and 4 IDE/SATA USB adapters, and all 
the hardware seems to work.  So far, so good.

The problem is that the disks use the v0.90 metadata format, and they 
came from a big-endian system, not a little-endian system.  MD 
superblocks *since* v0.90 are endian-agnostic, but back in v0.90, the 
superblock was byte-order specific.

mdadm(8) on an Intel processor refuses to acknowledge the existence of 
the superblock.  Testdisk detects it and correctly identifies it as a 
Big-endian v0.90 superblock.

I'm reluctant to blindly do a forced --create on the four disks, because 
I'm not 100% certain of the RAID topology; there are at least two RAID 
devices, one of which was hidden from the user, so I have no a-priori 
knowledge of its RAID level or layout.

The filesystems on the md(4) devices are, AFAIK, all XFS, and so should 
(hopefully) not have any endianness issues.

I can't find any modern big-endian Linux systems... looks like all the 
ARM distros run in little-endian mode.

Any suggestions on the best way to move forward?


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